security were trying to tell me I was not allowed to take pictures of the buildings using a tripod. I did not argue, since I was not planning more shooting anyway that night.

police was much more polite, they stopped me under Section 44 Terrorism Act 2000 and they were extremely careful not to upset me. they were only concerned that i might have any forbiddem items with me, weapons and explosives. they did not interfere with my photography.